Method of operating a double bed warp knitting machine



Aug. 12, 1969 K. KOHL 0, 58

METHOD OF OPERATING A DOUBLE BED WARP KNITTING MACHINE Filed March 9,1967 2 Sheets-Sheet l INVENTOR= KARL KoHL A q 9 MT" Aug. 12, 1969 KQHL3,460,358

METHOD OF OPERATING A DOUBLE BED WARP KNITTING MACHINE Filed March 9,1967 "2 Sheets-Sheet 2 INVENTOR KARL KOHL United States Patent Ofice3,460,358 Patented Aug. 12, 1969 3,460,358 METHOD OF OPERATING A DOUBLEBED WARP KNITTING MACHINE Karl Kohl, Otfenbacher Landstr. 20, Hainstadtam Main, Germany Filed Mar. 9, 1967, Ser. No. 621,873 Claims priority,application Germany, Mar. 10, 1966, M 68,708 Int. Cl. D04b 23/02 US. C].66-87 1 Claim ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION Theinvention relates to Raschel warp knitting machines, and particularly toa needle bar mechanism for a double needle bar Raschel machine, and to amethod of operating the machine.

The two needle bars of Raschel warp knitting machines known heretoforemove intermittently to shift the associated needles alternatinglybetween respective low and high positions in which the needles dwellduring guide bar movements, the needles of one bar dwelling in theknocking ofi. position while the needles of the other bar are at maximumheight.

This arrangement requires not only relatively long dwell times and rapidacceleration and deceleration of the needle bars, but also six changesin direction of movement for the guides during each knitting cycle (seeWarp Knitting Technology by D. F. Paling, Columbine Press, Manchester,England, 1965, p. 218). The inertial energy absorbed by the guide andneedle bar mechanisms during the reversals of movement is directlyrelated to the wear of these mechanisms. The known needle bar mechanismsrequire relatively complex cams, and it is not possible to employ crankdrives or their equivalents which can be built and maintained atrelatively low cost.

SUMMARY OF THE INVENTION I have found that the shortcomings of the knownneedle mechanisms can be avoided and the number of guide bar movementsreduced to a minimum by moving one needle bar from its low terminalposition toward the high position while the other bar is stillsubstantially in its terminal high position. More specifically, I moveone needle bar from its low or knocking-off position to a positionapproximately equidistant from the low and high positions while theother bar remains nearer its terminal high position than the lowposition.

Such a mode of operation permits the use of a mechanism which cyclicallyand continuously moves each needle bar in such a manner that thevertical positions of the bars are substantially sinusoidal functions oftime in the respective cycles. The cycles preferably are of equalduration and are offset in time.

It will be appreciated that the terms low, high," vertical and the like,as employed in this specification and the appended claim, relate merelyto locations spaced along the normal needle path and to the direction ofmovement in that path which has at least a major vertical component inmost warp knitting machines in practical use at this time. Thisinvention, however, does not rely on gravity for operativeness, and theafore-mentioned terms are not to be construed to limit this invention toa specific orientation in the field of terrestrial gravity.

Other features and many of the attendant advantages of this inventionwill readily become apparent from the following description of apreferred needle bar mechanism when considered in connection with theappended drawing.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 shows the needle bars and associated elements of a Raschel warpknitting machine of the invention in sectional side elevation;

FIG. 2 is the needle bar displacement diagram of a conventional Raschelwarp knitting machine;

FIG. 3 is the needle bar displacement diagram of a Raschel warp knittingmachine of the invention; and

FIG. 4 shows the needle bar mechanism of the invention in sideelevational section.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows as much of aRaschel warp knitting machine of this invention as is needed for adiscussion of the problem to be solved. Two parallel needle bars 1, 3carry respective rows of latch needles 2, 4, only one needle of each rowbeing Visible in the drawing. The needles are guided partly bystationary trick plates 1', 3' and move in respective longitudinal pathswhich extend mainly in a common vertical direction. This much is commonto this invention and to conventional Raschel knitting machines.

Contrary to common practice, the needles 2 are in or closely adjacenttheir position of maximum height while the hooks of the needles 4 areabove the associated trick plate 3', and approximately equidistant fromthe terminal high and low positions of their paths.

FIG. 2 diagrammatically shows the needle bar displacement of aconventional two-needle-bar Raschel warp knitting machine in the mannerof the afore-cited book by Paling. The needles 2 and 4 of the knownmachine, which in themselves may be identical with the needles shown inFIG. 1, are moved upwardly from the lowermost positions only after theneedles on the other needle bar have descended almost to their lowermostpositions. The relative position of the needles 2, 4 shown in FIG. 1cannot occur in a machine whose needle bar mechanism operates as shownin FIG. 2.

The needle bar displacement diagram of a machine of the invention, asshown in FIG. 3, consists of essentially sinusoidal curves, the ordinateof the diagram indicating the position of the needle bar or of theneedles, and the abscissa indicating time or angular displacement of arotary cam in the needle bar mechanism, as is conventional.

The cycles of needle bar oscillation are of equal duration and ofifsetor one half of the duration of each cycle so that the needles 2 moveupwardly in their path, as shown at 6 while the needles 4 are stillsubstantially at their highest point at 5. The dwell of the needles andof the associated needle bars in their terminal positions is infinitelyshort, and the oscillating vertical needle bar movement is continuous. Ihave found that such needle movement is entirely consistent with normalknitting operations.

A mechanism of the invention suitable for providing the sinusoidalneedle bar oscillations of FIG. 3 is illustrated in FIG. 4.

The needle bars 1, 3 carrying the needles 2, 4 are mounted on the freeends 7, 7a of respective guide arms 8, 8a whose other ends are pivotallysupported on shafts 9, 9a. A connecting rod 10 of adjustable lengthhingedly links the arm 8 to a rocker arm 11 movably mounted on a shaft12 and carrying two cam follower rollers 13 on its free end. The rollersrespectively engage the outer and inner cylindrical faces of a circularcam rim 14 on a disc 16 which is rotated by an eccentric shaft 15, asindicated by the arrow 17. When the shaft 15 is rotated by the knittingmachine drive to which it is connected in a conventional manner, notshown, the needles 2 move as described above with reference to FIG. 3.

The needles 4 are similarly moved by a connecting rod 10a hingedlyattached to the arm 8a, a rocker arm 11a oscillating on a shaft 12a andcarrying rollers 13a in engagement with the rim 14a of a cam disc 16afastened to an eccentric shaft 15:: for rotation in the direction of thearrow 17a. The linkage which transmits motion from the shaft 15 to theneedle bar 1 is a mirror image of that which transmits motion from theshaft 15a to the needle bar 3 in the illustrated position in which theneedles 2, 4 are on the same level. It will be understood, however, thatthe needles move in opposite directions from the illustrated positions,the respective cycles being offset approximately 180 of cam position orone half of a cycle.

The simple sinusoidal motion of the needle bars 1, 3 is brought about bya mechanism whose reciprocating elements move only slowly and with smallamplitude while the heavier elements 15, 16, 15a, 16a rotatecontinuously. It will be appreciated that the shafts 15, 15a arestatically and dynamically balanced for the eccentricity of the discs16, 16a in a conventional manner, not illustrated.

The Raschel knitting machine equipped with the needle bar mechanism ofthe invention is thus capable of higher operating speeds than anotherwise comparable conventional machine, its cams and other motiontransmitting elements have a longer useful life, and they can be builtat significantly lower cost.

It should be understood, of course, that the foregoing specificationrelates only to a preferred embodiment of the invention, and thatnumerous modifications and alterations may be made therein withoutdeparting from the spirit and scope of the invention set forth in theappended claim.

What is claimed is:

1. In a method of operating a Raschel knitting machine having two needlebars and means for oscillating the needle bars in respective pathsbetween respective terminal high and low positions, the improvementwhich comprises moving one of said bars from said low position thereoftoward the high position, while simultaneously moving the other bar fromthe high terminal position toward the low position, one of said barsbeing moved from the low terminal position thereof to a positionequidistance from the terminal position of said one bar, the other barbeing moved simultaneously from the high terminal position of the sameto a position equidistance from the terminal positions of said otherbar.

References Cited UNITED STATES PATENTS 1,796,579 3/1931 Rupf 66-87 XR2,273,246 2/1942 Anderson 66-87 2,333,697 11/1943 Boaler et al. 66-863,171,271 3/1965 Noe 66-87 XR 3,221,520 12/1965 Bassist 66-87 FOREIGNPATENTS 892,689 3/1962 Great Britain.

RONALD FELDBAUM, Primary Examiner

